Hydraulic flow control device



March 24, 1953 R. J. MILLER 2,632,476

HYDRAULIC FLOW CONTROL DEVICE Filed June 25, 1951 IN VEN TOR.

' the loader and tractor.

Patented Mar. 24, 1953 HYDRAULIC FLOW CONTROL DEVICE Raymond J. Miller, Detroit, Mich., assignor to Dearborn Motors Corporation, Birmingham, Mich., a corporation of Delaware Application June 23, 1951, Serial No. 233,184

This invention relates to a fluid flow control device for pressured hydraulic fluid systems.

The application of hydraulically operated motors to perform useful work are many and varied. In certain applications where the hydraulically operated piston of a cylinder is utilized -to raise a load, it is customary to permit such load to lowerby gravity by diverting the flow of pressured iiuid from the cylinder to the oil reservoir and bleeding the oil in the cylinder back to the reservoir.

A specific example of the above mentioned use of hydraulic power is the case of a loader mounted on a tractor wherein hydraulically operated pis- ,tons are utilized for elevating the loader boom to a raised transporting or unloading position. In this specific illustration, the loader boom is generally arranged to lower to the ground by gravity. To permit the loader boom to lower to the ground, the fluid in the cylinders is permitted to ow freely back to the sump or reservoir as the force of gravity drives the piston in the cylinder downwardly. Unfortunately, however, the rate of fall of the loader boom is relatively unrestrained so that the boom lowers at a rapid rate. This results in the loader boom striking the ground with considerable velocity which obviously is harmful to the various components of the boomY as well as Admittedly, a measure of control can be exercised in lowering the loader boom by proper manipulation of the control valve. This procedure, however, does not appreciably slow the rate of fall of the loader bucket as all that is accomplished is a lowering of the boom in a series of short drops; each drop producing a reaction on the loader frame and hence on the tractor as the downward movement of the loader is abruptly arrested. Another, and perhaps more serious drawback to so lowering the loader is the danger of rupturing the fluid supply conduits leading to the cylinder. The sudden stopping of the loader boom at any point sets up extremely large internal pressures in the cylinder and the conduits which occasionally results in rupture of such conduits.

Accordingly, it is an object of `this invention to provide an improved hydraulic fluid flow control device for automatically effecting a substantial reduction in the flow of pressured fluid through a conduit in one direction; for example, for controlling the rate ofl fluid discharge from a cylinder. Another object of this invention is to provide an improved hydraulic flow control device which may be conveniently adapted for use with any 4 a claims. (o1. 13s-45) pressured fluid system wherein the rate of fiow of pressured fluid in a certain direction may be automatically retarded, without interference with fluid flow in the opposite direction.

A further object of this invention is to provide a hydraulic flow control device which is operable in response to a pressure differential on opposite sides of such device for effecting a substantial reduction of iiow of the pressured fluid in one direction through such device.

The specific nature of this invention, as well as other objects and advantages thereof, will become apparent to those skilled in the art from the following detailed description, taken in conjunction with the one sheet of drawings on which, by way of preferred example only, is illustrated several embodiments of this invention:

On the drawings:

Figure 1 is a schematic view of a hydraulic system having a fluid operated motor in which the improved flow control device constructed in accordance with this invention is incorporated.

Figure 2 is an enlarged detail sectional view of a preferred form of the iiuid control device.

Figure 3 is a view similar to Figure 2 but showing the constriction of the iiuid passage of such device when subjected to hydraulic fluid flow in a certain direction. A

Figure 4 is a View similar to Figure 2 but showing a modified securing device for preventing axial movement of the ow control device.

Figure 5 is a further modification of the device shown in Figure 2.

Figure 6 is a modification of the structure shown in Figure 5 particularly as regards the ow control securing device.

As shown on the drawings:

The uid flow control device of this invention, to be shortly described in detail, is useful in numerous applications wherein it is desired to restrict the fluid passageway of a pressured fluid system in order to reduce the ow of fluid through such passageway in one direction in response to a sudden change in pressure dierential in the system. Its application is best suited to a pressured iiuid system which incorporates a hydraulic cylinder with cooperating piston wherein the power strokeof the piston is utilized to move a load, and where gravity acts upon such load to return the piston to its original position.V In this case, it is desirable that the fiuid bled from the cylinder pass through a restricted orifice to substantially reduce the rate of flow of the4 fluid, and hence the rate of fall of the load.

Accordingly. there is shown schematically in Figure 1 a pressured fluid system which includes a hydraulic cylinder C having a cooperating piston R. A pump P delivers pressured hydraulic fluid from a sump or reservoir S through a conduit B, in which a hydraulic flow control device FC is inserted, to one end of cylinder C. A valve V is connected in series with pump P whereby pressured fluid from pump P may be selectively diverted to cylinder C or returned to sump S through a conduit D. When valve V is positioned to divert the pressured fluid from pump P back to the sump, the hydraulic fluid contained in cylinder C will then be drained back to sump S also through conduit D.

In Figure 2 there is shown a preferred form of the hydraulic iiow control device FC which comprises a hollow cylinder I0 of resilient, ruby ber-like material. The resilient cylinder I0 snugly engages the inner wall of conduit B and such cylinder is provided with an axial bore Illa. Cylinder l0 is positioned in conduit B between valve V and cylinder C and is preferably located relatively close to cylinder' C. An annular groove l 0b is provided in the right hand end face of resilient member I0, as best shown in Figure 2, and such recess is preferably concentric with axial bore ma. A disc Il having an axial aperture Hul is placed against the right hand face of resilient member i0 so that aperture lla is in alignment with axial bore ma of the resilient member I9.

An annular groove I2 is provided in the interior wall of conduit B next to disc l l and a snap ring I3 is forced into annular groove l2; thus, snap ring I3 providesY a stop against which disc Il abuts to restrict axial movement of resilient member l0 in a right hand direction, as shown in Figure 2. Disc l l closes off the outwardly opening recess Ib provided in resilient member l0. However, a plurality of transverse holes lib in disc ll communicate with recess lb for a purpose to be later described.

hen it is desired to utilize piston R for raising a weight W, valve V is adjusted to permit pressured iiuid from pump P to enter cylinder C.

The pressured uid iiows through conduit 'B and .I

through the iow control device FC. The pressured fluid passes through aperture Hd of disc il, thence through the axial bore lila of resilient'member lil. Simultaneously, however, pressured iiuid enters annular recess lh in resilient f member It through tranverse holes llb in disc Therefore, no appreciable deformation of resilient member le results when pressured uid from pump F flows through the hydraulic fluid flow control member Hl as the pressure on both sides of resilient member lll are equalized and hence axial bore Ilia is not constricted.

When pressured fluid from pump P is diverted back to the sump by manipulation of valve V, hydraulic iiuid will then be bled cut of cylinder C to return to sump S through conduit D. When such happens, however, the pressure on the pump side of the resilient member lil immediately drops to a Ylow value while the weight W acting against piston R through the force of gravity maintains a relatively high pressure on the other side of resilient member lil. The fluid pressure in annular recess Ich is also reduced, due to the apertures lib. Hence, the pressure differential between the opposite sides ci resilient member l0 acts against the left hand end area of resilient member it to deform such member to the shape shown in Figure 3 and thus constricting bore iia as shown at file. Constriction of bore la substantially reduces the rate of flow of pressured hydraulic fluid through such bore, thus increasing'the length of time required to drain the uid from cylinder C and hence eiiecting a substantial reduction in the lowering rate of weight W. Furthermore, the extent of such constriction is a direct function of the pressure differential, hence shock loads are effectively minimized.

It will be noted that the resilient member lil is compressible in response to a pressure difierential between its opposite ends and only when the now of hydraulic fluid is from the cylinder C to the sump S.Y Such response may be referred to as a unidirectional pressure differential response which simply means that resilient member l0 is compressed only by a pressure differential producing one direction of flow of the vhydraulic iiuid through such resilient member,

but is unaffected by a pressure differential producing direction or" flow in the opposite direction. Of course, since amount of constriction produced by resilient member it is a function of the pressure diierence, the rate of lowering movement of the piston R is substantially independent of the mass of load weight W.

Figure 4 illustrates a modified arrangement for restricting axial movement of resilient member i. Such device comprises a collar hi having inwardly facing edge flanges lfla and Mb respectively provided on the opposite edges there- The collar lli surrounds resilient member l0 and the disc il is placed between resilient member iii and the iiange la, as shown in Figure 4. Piange lfd; can engage the left hand end face of resilient member l), or if preferred, a Washer E may be placed between iiange Mb and resilient member as shown. When resilient member i6 and disc El are joined together by collar lli, the entire assembly is then press-fitted within the bore of conduit B. Thus, the tight lit produced between collar iii and conduit B effectively resists axial movement of the assembly under the influence of an unbalanced hydraulic pressure within the conduit B.

Figure 5 illustrates a further modified form of the hydraulic ow control device wherein a resilient compressible member I6 of annular, U- shaped, cross section is provided for insertion in conduit B. in this modication, resilient member' it has an annular groove i619 formed in its outer periphery. An axial bore Hic is provided in resilient member i6 and an angularly directed iiuid passageway ltd communicates groeve 55h with the end of axial bore 16o, remote from cylinder C. This iuid passageway IBd exits at a point adjacent the right hand end face of resilient member l5. A pair of washers il and iii are respectively provided on opposite sides of resilient member i6, the resilient member I5 being bonded to one of the washers I? or I8. Resilient member I6 and washers l1 and I8 are held in assembled relationship within a desired location in conduit B by a pair of collars I9. Collars i9 are respectively provided with an edge flange les. Collars I9 are assembled within conduit B, one inside of the other, with the edge iianges disposed in opposed relationship so that such flanges will respectively engage the end faces of washers Il and i8. Collars i8 are press-ritted into conduit B so that axial movement of the resilient member l is thereby efiectively eliminated.

A modification of the construction shown in Figure 5Vis illustrated in Figure 6. In such figure resilient member i6 is fitted within a collar 20 which has an edged flange Zta. Collar 2t is press-fitted into the bore of conduit B and resilient member I6', similar to resilient member I6, has a peripheral ange Ia which is flared outwardly somewhat, as shown in Figure 6, to contact the inner wall of collar 20. VA washer 2| abuts flanges 20a of collar 20 and resilient member I6 abuts washer 2l. It will be appreciated that the fwasher 2| can readily be eliminated by increasing the radial width of flange 20a against,

which the adjacent face of resilient member I6 can abut.

The modications illustrated in Figures 4, 5 and 6 function in substantially the same manner as that described for the construction illustrated in Figure 2, hence, further description as to the operation of such modifications is not believed necessary.

From the above description, it is clearly apparent that there is here provided an improved uid flow control device which is not only simple in design and economical to manufacture, but is positive in operation to unidirectionally reduce the rate of iluid ow in a conduit in response to creation of a unidirectional pressure diierential in such conduit. This control device is not limited to use in any one particular hy- I claim:

1. For use in a reversible flow fluid conduit, a unidirectional flow control device of resilient material positionable in said conduit, said ow control device having a passage therethrough permitting fluid ilow through said conduit, said flow control device dening a recess separate from said passage, said recess being in fluid communication with said conduit only at one end of said flow control device, whereby a pressure differential across said ow control device producing flow through said iiow control device toward said one end produces a distortion of the resilient material of said ow control device surrounding said recess to constrict said passage.

2. The combination deiined in claim 1 wherein said passage comprises an axial bore through draulic system, but has a large number of, ap-

plications wherein an automatic unidirectional restriction` of the flow of pressured fluid in the system is desired in order that the rate of movement of the hydraulic piston in the system may be appreciably slowed.

It will, of course, be understood that many details of construction may be varied through a wide range Without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

said flow control device and said recess is of annular configuration surrounding said passage.

3. The combination dened in claim 1 plus a rigid plate abutting said one end of said ow control device, said plate having a rst aperture aligned with said passage and a second aperture communicating with said recess.

RAYMOND J. MILLER.

REFERENCES CITED The following references are of record in the iile of this patent:

UNITED STATES PATENTS Number Name Date 1,840,311 Du Bois l Jan. 12, 1932 2,389,134 Brown Nov. 20, 1945 2,418,325 Wassall Apr. 1, 1947 2,515,073 Binnall et al. July 11, 1950 2,568,519 Smith Sept. 18, 1951 

